/*
 * Copyright (C) 2008 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.gson;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * A class representing an array type in Json. An array is a list of {@link JsonElement}s each of
 * which can be of a different type. This is an ordered list, meaning that the order in which
 * elements are added is preserved.
 *
 * @author Inderjeet Singh
 * @author Joel Leitch
 */
public final class JsonArray extends JsonElement implements Iterable<JsonElement> {
    private final List<JsonElement> elements;

    /**
     * Creates an empty JsonArray.
     */
    public JsonArray() {
        elements = new ArrayList<JsonElement>();
    }

    @Override
    JsonArray deepCopy() {
        JsonArray result = new JsonArray();
        for (JsonElement element : elements) {
            result.add(element.deepCopy());
        }
        return result;
    }

    /**
     * Adds the specified boolean to self.
     *
     * @param bool the boolean that needs to be added to the array.
     */
    public void add(Boolean bool) {
        elements.add(bool == null ? JsonNull.INSTANCE : new JsonPrimitive(bool));
    }

    /**
     * Adds the specified character to self.
     *
     * @param character the character that needs to be added to the array.
     */
    public void add(Character character) {
        elements.add(character == null ? JsonNull.INSTANCE : new JsonPrimitive(character));
    }

    /**
     * Adds the specified number to self.
     *
     * @param number the number that needs to be added to the array.
     */
    public void add(Number number) {
        elements.add(number == null ? JsonNull.INSTANCE : new JsonPrimitive(number));
    }

    /**
     * Adds the specified string to self.
     *
     * @param string the string that needs to be added to the array.
     */
    public void add(String string) {
        elements.add(string == null ? JsonNull.INSTANCE : new JsonPrimitive(string));
    }

    /**
     * Adds the specified element to self.
     *
     * @param element the element that needs to be added to the array.
     */
    public void add(JsonElement element) {
        if (element == null) {
            element = JsonNull.INSTANCE;
        }
        elements.add(element);
    }

    /**
     * Adds all the elements of the specified array to self.
     *
     * @param array the array whose elements need to be added to the array.
     */
    public void addAll(JsonArray array) {
        elements.addAll(array.elements);
    }

    /**
     * Replaces the element at the specified position in this array with the specified element.
     * Element can be null.
     *
     * @param index   index of the element to replace
     * @param element element to be stored at the specified position
     * @return the element previously at the specified position
     * @throws IndexOutOfBoundsException if the specified index is outside the array bounds
     */
    public JsonElement set(int index, JsonElement element) {
        return elements.set(index, element);
    }

    /**
     * Removes the first occurrence of the specified element from this array, if it is present.
     * If the array does not contain the element, it is unchanged.
     *
     * @param element element to be removed from this array, if present
     * @return true if this array contained the specified element, false otherwise
     * @since 2.3
     */
    public boolean remove(JsonElement element) {
        return elements.remove(element);
    }

    /**
     * Removes the element at the specified position in this array. Shifts any subsequent elements
     * to the left (subtracts one from their indices). Returns the element that was removed from
     * the array.
     *
     * @param index index the index of the element to be removed
     * @return the element previously at the specified position
     * @throws IndexOutOfBoundsException if the specified index is outside the array bounds
     * @since 2.3
     */
    public JsonElement remove(int index) {
        return elements.remove(index);
    }

    /**
     * Returns true if this array contains the specified element.
     *
     * @param element whose presence in this array is to be tested
     * @return true if this array contains the specified element.
     * @since 2.3
     */
    public boolean contains(JsonElement element) {
        return elements.contains(element);
    }

    /**
     * Returns the number of elements in the array.
     *
     * @return the number of elements in the array.
     */
    public int size() {
        return elements.size();
    }

    /**
     * Returns an iterator to navigate the elements of the array. Since the array is an ordered list,
     * the iterator navigates the elements in the order they were inserted.
     *
     * @return an iterator to navigate the elements of the array.
     */
    public Iterator<JsonElement> iterator() {
        return elements.iterator();
    }

    /**
     * Returns the ith element of the array.
     *
     * @param i the index of the element that is being sought.
     * @return the element present at the ith index.
     * @throws IndexOutOfBoundsException if i is negative or greater than or equal to the
     *                                   {@link #size()} of the array.
     */
    public JsonElement get(int i) {
        return elements.get(i);
    }

    /**
     * convenience method to get this array as a {@link Number} if it contains a single element.
     *
     * @return get this element as a number if it is single element array.
     * @throws ClassCastException    if the element in the array is of not a {@link JsonPrimitive} and
     *                               is not a valid Number.
     * @throws IllegalStateException if the array has more than one element.
     */
    @Override
    public Number getAsNumber() {
        if (elements.size() == 1) {
            return elements.get(0).getAsNumber();
        }
        throw new IllegalStateException();
    }

    /**
     * convenience method to get this array as a {@link String} if it contains a single element.
     *
     * @return get this element as a String if it is single element array.
     * @throws ClassCastException    if the element in the array is of not a {@link JsonPrimitive} and
     *                               is not a valid String.
     * @throws IllegalStateException if the array has more than one element.
     */
    @Override
    public String getAsString() {
        if (elements.size() == 1) {
            return elements.get(0).getAsString();
        }
        throw new IllegalStateException();
    }

    /**
     * convenience method to get this array as a double if it contains a single element.
     *
     * @return get this element as a double if it is single element array.
     * @throws ClassCastException    if the element in the array is of not a {@link JsonPrimitive} and
     *                               is not a valid double.
     * @throws IllegalStateException if the array has more than one element.
     */
    @Override
    public double getAsDouble() {
        if (elements.size() == 1) {
            return elements.get(0).getAsDouble();
        }
        throw new IllegalStateException();
    }

    /**
     * convenience method to get this array as a {@link BigDecimal} if it contains a single element.
     *
     * @return get this element as a {@link BigDecimal} if it is single element array.
     * @throws ClassCastException    if the element in the array is of not a {@link JsonPrimitive}.
     * @throws NumberFormatException if the element at index 0 is not a valid {@link BigDecimal}.
     * @throws IllegalStateException if the array has more than one element.
     * @since 1.2
     */
    @Override
    public BigDecimal getAsBigDecimal() {
        if (elements.size() == 1) {
            return elements.get(0).getAsBigDecimal();
        }
        throw new IllegalStateException();
    }

    /**
     * convenience method to get this array as a {@link BigInteger} if it contains a single element.
     *
     * @return get this element as a {@link BigInteger} if it is single element array.
     * @throws ClassCastException    if the element in the array is of not a {@link JsonPrimitive}.
     * @throws NumberFormatException if the element at index 0 is not a valid {@link BigInteger}.
     * @throws IllegalStateException if the array has more than one element.
     * @since 1.2
     */
    @Override
    public BigInteger getAsBigInteger() {
        if (elements.size() == 1) {
            return elements.get(0).getAsBigInteger();
        }
        throw new IllegalStateException();
    }

    /**
     * convenience method to get this array as a float if it contains a single element.
     *
     * @return get this element as a float if it is single element array.
     * @throws ClassCastException    if the element in the array is of not a {@link JsonPrimitive} and
     *                               is not a valid float.
     * @throws IllegalStateException if the array has more than one element.
     */
    @Override
    public float getAsFloat() {
        if (elements.size() == 1) {
            return elements.get(0).getAsFloat();
        }
        throw new IllegalStateException();
    }

    /**
     * convenience method to get this array as a long if it contains a single element.
     *
     * @return get this element as a long if it is single element array.
     * @throws ClassCastException    if the element in the array is of not a {@link JsonPrimitive} and
     *                               is not a valid long.
     * @throws IllegalStateException if the array has more than one element.
     */
    @Override
    public long getAsLong() {
        if (elements.size() == 1) {
            return elements.get(0).getAsLong();
        }
        throw new IllegalStateException();
    }

    /**
     * convenience method to get this array as an integer if it contains a single element.
     *
     * @return get this element as an integer if it is single element array.
     * @throws ClassCastException    if the element in the array is of not a {@link JsonPrimitive} and
     *                               is not a valid integer.
     * @throws IllegalStateException if the array has more than one element.
     */
    @Override
    public int getAsInt() {
        if (elements.size() == 1) {
            return elements.get(0).getAsInt();
        }
        throw new IllegalStateException();
    }

    @Override
    public byte getAsByte() {
        if (elements.size() == 1) {
            return elements.get(0).getAsByte();
        }
        throw new IllegalStateException();
    }

    @Override
    public char getAsCharacter() {
        if (elements.size() == 1) {
            return elements.get(0).getAsCharacter();
        }
        throw new IllegalStateException();
    }

    /**
     * convenience method to get this array as a primitive short if it contains a single element.
     *
     * @return get this element as a primitive short if it is single element array.
     * @throws ClassCastException    if the element in the array is of not a {@link JsonPrimitive} and
     *                               is not a valid short.
     * @throws IllegalStateException if the array has more than one element.
     */
    @Override
    public short getAsShort() {
        if (elements.size() == 1) {
            return elements.get(0).getAsShort();
        }
        throw new IllegalStateException();
    }

    /**
     * convenience method to get this array as a boolean if it contains a single element.
     *
     * @return get this element as a boolean if it is single element array.
     * @throws ClassCastException    if the element in the array is of not a {@link JsonPrimitive} and
     *                               is not a valid boolean.
     * @throws IllegalStateException if the array has more than one element.
     */
    @Override
    public boolean getAsBoolean() {
        if (elements.size() == 1) {
            return elements.get(0).getAsBoolean();
        }
        throw new IllegalStateException();
    }

    @Override
    public boolean equals(Object o) {
        return (o == this) || (o instanceof JsonArray && ((JsonArray) o).elements.equals(elements));
    }

    @Override
    public int hashCode() {
        return elements.hashCode();
    }
}
